Sri Murwani
Epidemiology is the study of the distribution, the dynamics, and the determinants of diseases in populations. The risk of virus infection and/or clinical disease is determined by characteristics both of the virus, and the levels of innate and acquired resistance in the community [1]. Virus transmission is affected by behavioral, environmental, and ecological factors. Knowledge of these factors contributes to evidence-based policy decisions as to how best to control and prevent virus diseases. Considerable use of genome sequencing of isolates now provides useful information as to the identification of outbreak sources as well as informing the design and testing of candidate vaccines [2]. Epidemiology is the study of the distribution, the dynamics, and the determinants of diseases in populations. The risk of virus infection and/or disease in a human population is determined by the characteristics both of the virus, and of susceptible individuals and of the host population such as innate and acquired resistance. In addition, virus transmission is affected by behavioral, environmental, and ecological factors. Virus epidemiology aims to meld these factors using quantitative measurements to provide a rational basis for explaining the occurrence of virus diseases and for directing disease-control measures, in particular the identification of outbreak sources and how best to implement prevention strategies [3]. Epidemiology can also help to clarify the role of viruses in the etiology of diseases, understanding the interaction of viruses with environmental determinants of disease, determining factors affecting host susceptibility, clarifying modes of transmission, and the testing of vaccines and therapeutics on a large scale. Epidemics are peaks in disease incidence that exceed the endemic baseline or expected rate of disease. The size of the peak required to constitute an epidemic is arbitrary and is related to the background endemic rate and the rate of clinical to sub-clinical infection [4]. Sometimes a few cases of a disease that arouse anxiety because of their severity, for example encephalitis, will be loosely termed an “epidemic” whereas a few cases of influenza will not, but the term strictly implies unusually wide and rapid spread of infection within the population.
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